The stem juice of sweet sorghum is rich in fermentative sugar and is a desirable alcoholic fermentation material. It is difficult to measure the juice Sugar content in the process of production. The sugar content is commonly expressed with juice brix degree, but the relation between sugar content and brix degree has not been very cleared The objective of this study was to find out their relation and tell the sugar content by means of the measurement of juice saccharine more accurately, which may provide a theoretical basis for crop breeding and fermentation. In addition to fermentative sugar, other kinds of sugars are also found in the stem juice of sweet sorghum. The acquirement of the contents of different sugars is beneficial to the enhancement of alcohol production rate. There are also some ammonia acids and minerals in the juice, measuring their contents enables us to use sweet sorghum better with multi-purpose.

The current research determined the sugar content and brix degree of different varieties in different growth stages. The results gave a scientific basis for the arrangement in the varieties and their sowing dates, so as to prolong the fermentation period and increase the efficiency of the alcoholic fermentation device usage. Therefore, this study has a practical instructive meaning for sweet sorghum breeding as well as the cultivation or fermentation, and the materials and methods as follows:

At different period, two plants as a sample in each plot were randomly chosen for measuring their stem weights, and then juice of the stems were extracted by IJ-305 squeezer, and finally measuring glucose fructose sucrose content by high performance liquid chromatography, starch and total sugar content by another one spectrophotometry, Amino acid content by high speed amino acid analyzer, crude protein content by nitrogen and protein analyzer, total Phosphorus content by ammonia Vanadate and ammonia molybdenum spectrophotometry, mineral element content by atomic absorption spectrometry.

4.1.1 Brix degree in sweet Sorghum stem

A. Changing Law of Brix Degree of juice in sweet sorghum stem

The research shows that the brix degree of juice in sweet sorghum stem is lower before heading stage. After that, with the grain forming, the brix degree straightly increase towards its maximum at harvest stage. For whole

Tab.4.1.1 Brix Degree of different Varieties at different period

variety

time (D/M)

26/8

5/9

13/9

4/10

10/10

15/10

29/10

RIO

12.2

15.5

16.8

17.0

17.0

15.5

14.5

Shennong No.2

11.5

12.7

15.3

14.5

14.5

13.0

9.0

6AX1022

12.2

15.0

17.2

14.3

14.5

14.0

11.0

Jitian 2

10.1

12.8

15.8

15.5

14.0

14.0

12.2

Longshi 1

14.5

16.3

18.0

13.0

14.0

12.5

11.5

6AXN249

8.4

10.8

15.7

15.0

12.5

11.2

9.8

Stem or each section of the stem, its brix degree rises as the plant growing it is the period within heading the first ten days and the third ten days that the degree increases distinctly. From Tab.4.1.1, it is known although among the six varieties, the brix degree changing law and the maximum degree period are not same, the present time of the maximum value is highly according to the harvest stage. Therefore, sweet sorghum should be harvested at the grain maturing stage in which both high sugar content and grain yield can be obtained.

B. Analysis on Brix Degree of Juice in internodes and Whole Stem

From Tab.4.1.2, it can find that the brix degrees are different in every internodes, the tendency is low-high-low from top to low position, and most

Tab.4.1.2 internode brix degree of different varieties (1990.8.26)

variety

internode

2

4

6

8

10

12

14

Rio

14.2

14.5

15.0

14.5

14.0

13.0

13.5

14.5

14.3

14.0

12.6

12.7

11.5

13.0

13.2

13.8

14.2

13.5

12.5

Shennong No.2

10.2

11.5

12.5

13.4

13.0

11.2

10.5

11.5

11.7

12.0

11.5

10.0

9.5

16.3

15.0

14.2

12.0

11.0

6AX1022

15.0

14.0

15.3

13.0

15.3

15.0

11.3

10.5

12.3

11.1

11.5

10.0

8.5

Jitian 2

13.0

10.5

10.3

8.6

9.0

13.5

12.6

12.5

12.3

13.7

11.2

11.1

10.6

10.0

Longshi 1

15.0

15.8

16.0

16.1

12.4

13.0

14.0

15.5

16.4

14.2

6AXN249

8.2

10.1

9.5

9.0

7.0

8.3

8.0

8.2

7.5

14.0

14.3

13.0

11.0

9.5

8.7

Varieties highest brix degrees are occurred at 4 to 6th internodes from the top. In order to exactly measure the brix degree of stem, the juice for test should be extracted from whole stem.

Varieties highest brix degrees are occurred at 4 to 6th internodes from the top. In order to exactly measure the brix degree of stem, the juice for test should be extracted from whole stem theoretically. However, it is impossible to extract the stalk juice on field. The purpose of this trial is to find a way of testing brix degree by one internode to present the one of whole stem, Through testing the brix degree of each internode of a stem (as shown in Tab. 4.1.3). it is known that the brix of some internodes can not present the one of whole stalk, because the brixes are different for each internode. The average brix degree for all internodes are suggested to be as the one of whole stalk.

C. Comparison of Brix Degree of Different Varieties in the Same Period

Variance analysis of test results in different three days indicates that the difference is significant between brix degrees of different varieties. The test shows that the brix degree of Longshi 1 is the highest and the one of 6AXN249 is the lowest. There RIO, 6AX1022, Shennong No.2 and Jitian 2. in the midst of them. Statistics analysis shows before September, the brix degree of Longshi 1 is the highest, but with the growing of plants, at the beginning of September, the difference becomes smaller until no any gap between them. Thus, for prolonging the period of ethanol production from sweet sorghum, the order of seeding time are Longshi 1, Shennong No.2.

There are plenty of sugar in the juice of sweet sorghum stem. However, how many kinds of sugars exist in the juice is still a question. Based on our results, it was not sufficient to regard the sum of sucrose, glucose and fructose as the total sugar content traditionally. The test by enthrone spectrophotometry shows the following kinds of sugars are existed in the juice of sweet sorghum, stem: xylose, ribose, arabinose, fructose, sorbose, galactose, mannose, sucrose glucose, polyglucose and glucoses. Of course, the total sugar content is much more than that of sucrose, glucose and fructose. Based on the test results as shown in Tab.4.1.4, the variance and the multiple comparison have proved both the variety and test time have a significant influence on sugar content. So in order to prolong the period of ethanol production and get more sugar, it is suggested that not only the varieties should be combined with but also the different harvest time should be planned.

4.1.3 Relationship between, Total Sugar Content and Brix Degree

It has been doubted if the brix degree equals to sugar content. The experiment confirmed that the sugar content usually larger than brix degree. Variance analysis also indicates that sugar content (Y) of all varieties have a significant(!y) or extremely significant (!y !y) Line correlation with brix degree (X). Their line correlations can be respectively described as Tab 4.1.5.

Tab.4.1.4 Total sugar content of different variety in different period

Variety

Time (D/M)

4/10

10/10

15/10

25/10

29/10

Rio

22.14

19.44

16.92

16.20

16.20

Shennong No.2

20.52

19.04

16.63

14.11

10.82

6AX1022

16.13

19.26

16.02

13.29

10.81

Jitian 2

21.24

16.20

15.95

10.29

13.86

Longshi 1

16.67

18.68

12.96

7.96

10.26

6AXN249

20.52

17.96

13.07

11.52

10.67

Tab.4.1.5 Line Correlation between Sugar Content and Brix Degree

Variety

Equation

R

RIO

Y= -7.712+ 1.660X

0.89

Shennong No.2

Y= -4.714+ 1.662X

0.97

6AX1022

Y= -5.624+ 1.601X

0.90

Jitian 2

Y= -11.080+ 2.008X

0.97

Longshi 1

Y= -14.176+ 2.283X

0.94

6AXN249

Y= -9.549+ 2.052X

0.97

Tab.4.1.5 shows the sugar content with brix degree has a positive correlation. Based these equations, we can predicts the sugar content by measuring the brix degree easily. In order to use equation more convenient, we dealt with total sugar content (y) and brix degree (x). Table 4.1.6 shows the mean Y and mean X of the 6 varieties at different periods. Variance analysis appears extremely Significant between Y andX, Our aim is this equation can be used in other varieties besides the tested ones.

The line-correlation is:

y= -10.24+ 1.974x

Tab.4.1.6 Mean total sugar content and mean brix degree

time

time (D/M)

4/10

10/10

15/10

25/10

29/10

brix degree

14.9

14.4

13.4

11.2

11.3

total sugar content

19.54

18.43

15.26

12.2

12.1

4.1.4 Contents of some main sugars

A. Glucose content

Glucose is dextrose hose being present in all plant organs and tissues. Glucose has two crystals: one is µ -glucose separated out from alcohol or water solution under room temperature, with melting point of 146°C and [µ]200+ 112.2° C; another is b -glucose separated out from hot pyridine solution of 148 to 150 °C, [µ]200+ 18.7°C.

D-glucose is the only form in natural world with a saccharinely of 0.69 times as much sucrose.

Glucose is the primary material of plant photosynthesis. For C4 species, besides the Calvin cycle of glucose formation, there is also a four-carbon pathway for CO2 fixation in mesophyll cells, therefore they have great potential for CO2 assimilation.

Sweet sorghum is a C4 crop, with lower CO2 compensation point, higher light saturation point and weak photorespiration, and consequently has a higher biological yield.

Glucose is a substrate of respiration and also a component of sucrose, starch and cellulose.

As a reducing sugar, glucose can be fermented by saccharomycete. In fermentation, acetic aldehyde and CO2 are produced through decarboxylation of pyruvic acid formed from the dehydrogenation of glucose, then acetic aldehyde is dehydrogenated and alcohol is produced. The whole process is under anaerobic and enzymatic conditions, which is known as alcohol-producing fermentation.

Glucophosphate ester can be transformed into fructophosphate ester by isomerase. Glucose can form starch either with ADPG (or UDPG) as offering under amylosucurose, or with glucophosphate ester as offering under phosphatase transferring glucose to an introducer. Cellulose is formed through times of translocation of glucose unit to the glucose chain from GDPG under transferase.

Tab.4.1.7 Glucose content of different Varieties (%) 1989

Variety

Time (D/M)

27/9

6/10

12/10

T*

Rio

1.0

2.2

1.70

4.2

Shennong No.2

2.3

2.1

2.4

3.2

6AX1022

2.2

1.9

2.7

4.8

Jitian 2

3.4

3.1

4.0

5.6

Longshi 1

2.1

1.7

1.8

5.4

T: sampled on October 6 and measured on October 12

From Tab.4.1.7, samples were obtained for different varieties in different growth stages. The juice was extracted and was to be analyzed for glucose content. The variance analysis showed that both varieties and growth stages affected glucose content very significantly.

The multiple comparison results using SSR method showed that Jitian-2 was highest in glucose with 1.762 difference from the lowest Rio; the glucose content of Jitian 2 had significant difference with that of Longshi 1 and 6AX1022, very significant with that of Shennong No.2 and Rio; there is no significant difference among 6AX1022, longshi 1, Shennong No.2 and Rio. As for the growth stages, October 6 sampling, then stored until October 12 for extraction and analysis showed highest glucose content, Very significantly different from other stages, while there is no significant difference among the latter.

In summary, varieties were an very important factor determining the glucose content, there were differences in glucose among varieties; there were no significant differences in that among growth stages, but the stored sample after harvest gave obviously higher glucose content.

B. Fructose content

Fructose is a hexose with reductive character. b -pyranofructose is its free type, and b -furanofructose the combined type. The natural fructose is all levulose, µ -D-fructose with [µ]200 -63.6°C, b -D-fructose with [µ]200-133.5°C. Fructose is a colorless crystal with strong hygroscopicity. It is sweetest among the sugars, with a saccharinity of 1.15 to 1.5 times as much as sucrose, so it can be used as nutrient and as preserving agent.

Fructose can be combined with saccharomycete. It is first transformed into fructophosphate ester, and then enter the EMP pathway. The sucrose synzyme existing in high plants can use uridine diphosphate glucose (UDPG) as the offering of glucose to form sucrose with fructose. It can also be synthesized under sucrose phosphate using UDPG as offering of glucose and 6-p-fructose as receptor. The first product of above reaction is phosphorescence that is then hydrolyzed to sucrose under phosphate.

In plant photosynthetic tissue sucrose phosphoresce is more active, while in non-photosynthetic tissue sucrose synzyme is mere active.

Tab.4.1.8 shows Fructose contents of 5 varieties, Rio.Shennong No.2, 6AX1022, Jitian 2, Longshi 1, in 4 growth stages, September 27, October 6, October 12 and October 6 sampling but October 12 measuring, were analyzed. The results indicated that varieties were not important determinant for fructose content. Of the 5 varieties, only Jitian 2 was significantly different in fructose content from Rio, whereas there was no big difference among others. However, growth stages affected fructose content very much. October 6 sampling but October 12 measuring got a highest fructose content, very significantly different from other stages among which no significant difference was found. Like glucose, fructose increased very significantly after storage. This means that storage exerts a large effect on fructose content.

Tab.4.1.8 Fructose content in stem juice (%) 1989

Variety

Time (D/M)

27/9

6/10

12/10

T*

Rio

0.8

1.7

1.4

3.6

Shennong No.2

1.9

1.7

2.0

2.6

6AX10226

1.8

1.5

2.3

4.4

Jitian 2

2.6

2.4

3.0

4.3

Longshi 1

1.8

1.5

1.6

4.8

T: Sampled on October 6 and measured on October 12

C. Sucrose content

Sucrose is a widely existed disaccharide in natural world, and it is a non-reducing sugar. It is found in all photosynthetic plants, but is more in cane and beet so it is popularly called cane sugar on beet sugar sucrose plays an important role in plant physiology, it is not only the main product of photosynthesis, but also the main form of storage and accumulation of carbohydrate, sucrose is also the transportation form of carbohydrate within plant.

Sucrose is disaccharide, when hydrolyzed, one molecule D-glucose and one molecule D-fructose are produced sucrose can be looked as a product of a -hydroxyglucoside and b -hydroxyfrucoside losing one molecule of water. The mixture of glucose and fructose formed from sucrose hydrolysis is defined as invert sugar.

There is no hydroxyl group of glucoside in sucrose molecule, so sucrose cannot be changed to open chain structure. Therefore sucrose has no multiracial effect, can not form osazone. It has no reductive effect, is non-reducing sugar sucrose is dextrose with [a]20 0=66.5°C. Saccharomycete can ferment sucrose.

Tab.4.1.9 Sucrose content in stem juice (%) 1989

Variety

Time D/M)

27/9

6/10

12/10

T*

Rio

6.9

9.0

5.7

7.0

Shennong No.2

3.6

5.9

5.5

9.6

6AX1022

3.4

7.2

5.5

9.2

Jitian 2

2.2

3.7

7.4

2.8

Longshi 1

7.5

6.9

9.4

10.0

T: Sampled on October 6. and measured on October 12

Tab.4.1.9 shows the sucrose content of the tested varieties. It could the seen from the variance analysis and multiple comparison that varieties and growth stages had no significant effect on sucrose, and the content is relatively stable. Thus sucrose content does not greatly influence the fermented sugar and total sugar content.

D. Pooled analysis of glucose, fructose and sucrose

From Table 4.1.10, Rio, Shennong No.2, 6AX1022, Jitian 2 and Longshi 1 were analyzed for sugar contents on September 27, October 6, October 12, and October 6 sampling but October 12 measuring. From Fig 1, we can know the differences among the 3 kinds of sugar contents.

From the above 3 factors randomized block experiment, conclusions were made as follows:

a. October 6 sampling and then stored until October 12 showed very significantly higher in sugar content than September 27, October 6 and October 12, indicating that storage could increase sugar content. The other 3 stages had no significant differences in sugar content, meaning that sugar content was stable during that period.

b. sucrose content was very significantly different with glucose and fructose, while glucose content was not obviously different from fructose. This mean that sucrose prevailed over glucose and fructose in the stem sap of sweet sorghum.

d. The glucose content in Jitian 2 varied significantly with those of the other 4 varieties.

e. The fructose content showed no significant variance among the studied varieties.

Tab.4.1.10. Glucose, Fructose, sucrose content in stem juice of different varieties at different period (%) 1989

Time (D/M)

27/9

6/10

variety

Glucose

Fructose

Sucrose

Glucose

Fructose

Sucrose

Rio

1.0

0.8

6.9

2.2

1.7

9.0

shennong No. 2

2.3

1.9

3.6

2.1

1.7

5.9

6AX1022

2.2

1.8

3.4

1.9

1.5

7.2

Jitian2

3.4

2.6

2.2

3.1

2.4

3.7

Longshi 1

2.1

1.8

7.5

1.7

1.5

6.9

Time (D/M)

12/10

T*

variety

Glucose

Fructose

Sucrose

Glucose

Fructose

sucrose

Rio

1.7

1.4

5.7

4.2

3.6

7.0

shennong No. 2

2.4

2.0

5.5,

3.2

2.6

9.6

6AX1022

2.7

2.3

5.5

4.8

4.4

9.2

Jitian2

4.0

3.0

7.4

5.6

4.3

2.8

Longshi 1

1.8

1.6

9.4

5.4

4.8

10.0

* T: Sampled on October 6 and measured on October 12

Fig.4.1.1 Glucose, Fructose and sucrose content in stem juice

4.1.5 Starch content

Starch is a material of white and colorless, existing in granule forms of spherical or oval depending on plant types. It consists of amylose and amylopectin, and in most case the former accounts for 10 to 20% and the latter 80 to 90% It transfers into D-glucose by complete hydrolysis and into maltose by partial hydrolysis.

The water solution of starch of dextrose with [µ]200 =201.5 to 205 °C. The mean specific weight is 1.5.

Looking at the structure of starch, we know that at the end position of the polyglucoside chain there is free semi-acetalhydroxyl. But starch generally does not present reductive character, because there is only one semi-acetal hydroxyl in every hundreds or even thousands of glucose units.

Tab.4.1.11 Starch content of stem juice (%) 1990

Variety

Time (D/M)

4 /10

10/10

15/10

25/10

29/10

Rio

0.32

0.27

0.16

0.03

0.07

Shennong No.2

0.99

0.23

0.37

0.06

0.02

6AX1022

0.30

0.16

0.12

0.09

0.07

Jitian 2

0.45

0.43

0.14

0.11

0.09

Longshi 1

0.26

0.29

0.04

0.02

0.06

6AXN249

0.41

0.45

0.37

0.03

Starch is the main storing form of sugar and energy in plants existing with great amount in seeds, fruits, root and stem tubers, and with small amount in leaves and stems.

Starch can not be fermented by saccharomycete directly, it needs to be dextrinized and saccharified, turning into fermentable, and then can be used to produce alcohol through fermentation.

Starch content was measured for 6 varieties, Rio, Shennong No.2, 6AX1022, Jitian 2, Longshi 1 and 6AXN249, at 5 growth stages, October 4, October 10, October 15, October 25 and October 29 (Table 11). Variance analysis and multiple comparison results showed that varieties had little affect on starch content, among the 6 varieties only Shennong No.2 and 6AXN249 exhibited significant difference. Growth stages affected starch content greatly starch content on October 4 was highest, very significantly different from those on the other stages except October 10. starch content on October 10 had no significant difference with those on October 4 and October 15, but had significant difference with these on October 25 and October 29. There were no significant differences in starch content among October 15, October 25 and October 29.

From the above analysis, we know that starch is very low in stem juice, it contributes in alcohol production with small amount so the stem juice of sweet sorghum is a good saccharine source. Therefore, the alcohol production with sweet sorghum stem as raw material does not require complicated technology and expensive equipments, also the production period is short because of some procedures being left out. It is a low cost and easily operated alcohol producing method.

As for starch content, early October is the best time for harvest when starch amount is high. starch can be utilized to produce alcohol through fermentation after saccharigation. Although starch content is not high, it is still important for a large production scale so the starch has also certain value in alcohol production.

4.1.6 Relation between total sugar and glucose, fructose and sucrose in stem juice

According to the preceding discussion that the total sugar in the juice includes some penthouse, hexose and polysaccharide. of these sugars, glucose, fructose, sucrose and starch have examined in order to learn some internal regularities.

Tab.4.1.12 and Tab.4.1.13 showed sugar contents of 5 varieties measured in 1989. The results in Table 4.1.12 were measured on October 12 immediately after sampling, and those in Table 4.1.13 were measured on October 12 after 6 days storage. From these tables we know that glucose, fructose and sucrose are the main parts of sugars in the juice, the sum of these 3 sugars is near to the total sugar amount but they are not the same thing, especially different sugars should not be simply summed up theoretically. So, the estimate of total sugar should be made by direct measurement or calculated according to the brix degree using the formula described earlier.

Table 4.1.12. Sugar Content in Stem Juice (%) 1989.10.12

Variety

Rio

Shennong No. 2

6AX1022

Jitian2

Longshi 1

total sugar content

12.60

12.20

14.40

10.90

18.35

Glucose

1.7

2.4

2.7

4.0

1.8

Fructose

1.4

2.0

2.3

3.0

1.6

Sucrose

5.7

5.5

5.5

7.4

9.4

Table 4.1.13. Sugar Content in Stem Juice (%) 1989

Variety

Rio

Shennong No. 2

6AX1022

Jitian2

Longshi 1

total sugar content

15.26

17.50

20.20

11.40

18.20

Glucose

4.2

3.2

4.8

5.6

5.4

Fructose

3.6

2.6

4.4

4.3

4.8

Sucrose

7.0

9.6

9.2

2.8

10.0

It is known that the transformation from glucose to sucrose under enzyme is a simple process. Furthermore, sugar and starch contents are different among varieties, so considerations should be made on choosing higher glucose and fructose or higher sucrose. Perhaps it is better to select higher glucose and fructose sweet sorghum considering that the transformation from glucose to sucrose or starch, and then starch and sucrose turning into glucose in the process of fermentation all consume energy.

4.1.7 Crude protein, amino acid and mineral component

The stalk of dual-purpose sweet sorghum for grain and feed contains much sugar. It is applicable for ensilage for its better palatability and easy lactic acid fermentation. The chopped fresh sweet sorghum stalk is put in gas-tight silo or tower, and through lactic acid fermentation becoming odorous, palatable with moderate sweet and sour and long keeping juicy feed for winter on the whole year use. The organic acids in the ensilage can promote the secretion of digestive gland, hence increase the domestic animal's digestibility for the feed. This ensilage has also an effect of light diarrhoea, therefore prevent animals from constipation. The ensilage of the stalk could be conducted after grain harvesting.

Moreover, because of the multiple nutrients in sweet sorghum juice, it has a foundation for being used in food production For example, sweet sorghum can be used to produce non-alcohol drink.

The present study determined the components of the juice, but the feed utilize the whole stalk Therefore the following discussion will focus mainly on the utilizing potential in food production.

A. Protein and amino acid content in stem juice

a. Protein content

In view of the food science, protein contributes not only to the nutritional values But also the color, fragrance, odor and texture of the food. So the measurement of protein in the stem juice and the research of its transformation in the process of drink production have important practical values.

Tab.4.1.14 Crude protein content in stem juice (mg/ml) 1989

Variety

Time (D/M)

Rio

Shennong No.2

6AX1022

Jitian2

Longshi 1

27/9

4.869

1.560

1.796

1.560

3.073

6/10

5.578

1.702

2.647

1.938

3.073

The crude protein in the stems is showed in Tab.4.1.14 for 5 varieties It increased in October Comparing to fruit juice, sweet sorghum stem juice contains no less protein, for example apple juice containing nitrogenous compounds 1.25mg/ml, pear juice containing 1.33 mg/ml.

b. Amino acid content

Protein and amino acid function as an organic buffering system keeping pH value stable in the body. The human essential amino acids must be obtained from food. The nutritional value of a drink depends not only on the amount of nutrients, but more importantly on the numbers of nutrients. Natural food contains basically all kinds of nutrients with stable proportion and amount, and is high in nutritional value, Tab.4.15 shows amino acid contents in sweet sorghum stem. Of the human essential amino acids, lysine, phenylalanine, valine, methionine, leucine, isoleucine and threonine are found in the juice, histidine essential to babies is also found. Tryptophan was not determined in this research.

B. Mineral components in stem juice

Only small part of minerals takes part in the formation of organic matter, the majority of them are in the state of inorganic salts or electrolyte maintaining osmotic pressure, adjusting pH state, also keeping protoplasm active and engaging in biochemical reaction. So it is necessary for a drink to contain some mineral elements. The minerals of different varieties in stem sap are showed in Tab.4.1.16.

Tab.4.15. amino acid content in stem Juice (mg/ml) 1989.10.6

Amino acid

Variety

Rio

Shennong No. 2

6AX1022

Jitian2

Longshi 1

aspartic acid

1.542

0.130

0.430

0.167

0.406

threonine

0.102

0.037

0.630

0.041

0.069

serine

0.166

0.042

0.069

0.049

0.057

qlutanic acid

0.523

0.160

0.328

0.197

0.410

glycine

0.074

0.039

0.067

0.090

0.074

alanine

0.096

0.048

0.071

0.060

0.189

veline

0.114

0.050

0.074

0.055

0.083

inethianine

0.044

0.027

0.040

0.035

0.043

isoleucine

0.057

0.031

0.036

0.024

0.038

leucine

0.140

0.065

0.080

0.055

0.100

lyrosine

0.064

0.025

0.019

0.012

0.022

pherylalanine

0.087

0.048

0.054

0.040

0.065

lysine

0.074

0.040

0.063

0.029

0.063

annonia

0.103

0.028

0.045

0.030

0.048

histidine

0.043

0.015

0.031

0.014

0.029

arginine

0.031

0.037

0.069

0.037

0.032

proline

0.091

0.056

0.064

0.055

0.037

Table 4.1.16 Mineral components in stem juice (ppm) 1989

Variety

elements

total phosphorus

K

Na

Ca

Ng

Fe

Mn

Rio

50

2200.80

15.56

92.85

8.4

84.21

91.14

Shennong No.2

50

1431.15

11.44

125.99

6.83

89.60

66.22

6AX1022

55

1603.35

7.48

196.82

7.35

101.97

99.01

Jitian2

35

904.05

1.24

100.94

3.68

97.74

144.90

Longshi 1

110

3087.00

25.61

151.31

7.87

96.20

99.43

Maintaining normal vital functions, a man needs to take certain amount of minerals, for example an adult needs 400 to 100mg calcium, 200 to 300mg magnesium, 0.9 mg iron a day. some satisfy the human need just from normal food, and some are not sufficient, which causes some kinds of illness. For this reason some fortified drinks with calcium and zinc have been developed in recent years to meet the requirement.

Making drink with sweet sorghum stem juice has great superiority because sweet sorghum is very productive and makes the resource for drink production very rich, and also because this drink is cheaper. Therefore the drink has stronger competitiveness for its low price.

According to the experimental results, the possibilities to make drink with the juice were studied. However, because of the influence of the formulation and the production technology some components of the raw materials may have some changes. Between the nutrients there are synergistic action and also antagonistic action, so the biological effects should be more considered. The drink made from sweet sorghum stem juice is not sufficient in acidity, and Vc content has not been determined yet, which remain to be studied .

Conclusion

A. The brix degree of internodes, measured in the center of every internode, were high in the middle position of the stem and low in the up and down place. The highest brix degree differed among varieties in internode position but for most varieties they occurred at 4 to 6th internode from the top.

The brix degree were measured at different stages, variance analysis and multiple comparisons were also made. The results indicated that Longshi 1 showed higher brix degree than other varieties before waxen maturity, and along with maturity the differences of brix degree were becoming smaller or ever non.

B. The total sugar content was affected very significantly by varieties and growth stages, Among the varieties, Rio and Shennong No.2 indicated higher, while Longshi 1 and 6AxN249 indicated lower. As for the time, October 4 to October 10 measured higher total sugar content, when all varieties had ripened so, the time of high sugar content was identical with the maturity.

C. It has long been concerned for the relation between brix degree and total sugar content. The measurement of total sugar is very inconvenient in practice. So measuring brix degree with WYT-1 hand sugar refractometer and then converting to the total sugar is desired. A correlation analysis for the brix degree and total sugar of sweet sorghum stem juice had been conducted that they had significant Linear correlation. The regression equations were made out for each variety in order to extend the relationship to other varieties, a general regression equation of total sugar and brix degree has been developed:

y= -10.24+ 1.974x

It has been tested that the frequency of less than 2% differences between the calculated and the measured total sugars is over 77%.

D. There were significant or very significant differences of glucose contents among the tested varieties, but were no significant differences of fructose and sucrose contents among them.

Among these three sugars, sucrose contents were very significantly different from glucose and fructose contents, while the latter two sugars were similar. This indicates that sucrose content in sweet sorghum stem juice is dominant and it keeps relatively stable along with the growth stages. It had been found from the measurement of sugars after one week's storage of the harvested stem that the storage had great effects on the glucose and fructose contents which increased, and had little effect on sucrose.

E. The total sugar content was very high in sweet sorghum stem juice, but not all of the sugars were fermentable. The fermentable glucose, fructose and sucrose were in dominance.

F. The starch contents were very low in the stem juice and no significant differences were found between varieties. The starch was higher at early October. Therefore, some treatments to the starch might be taken in the process of alcohol production, such as applying saccharification, in order to utilize the limited starch and increase alcohol producing rate.

G. Among the 6 tested varieties, Shenong 2 had the highest biological yield, Longshi 1 and 6AxN249 ripened earlier, Longshi 1 had higher sugar content by October. For a better variety arrangement, Longshi 1 could be taken as the first source of alcohol production, then in turns of Shenong No.2 and Rio. Thus not only the alcohol production period could be extended, but also the problems from storage could be reduced.

H. There are also certain amounts of amino acids and mineral elements in sweet sorghum juice, which provides possibilities for their multiple usage, especially in the use of soft drink production.

Alcohol production with sweet sorghum stem is a very complicated work . We can find some distances between theoretical and practical when evaluating the characters of the varieties, such as for the variety arrangement, the manpower, material resources and other things are involved. The objective of this study is to provide some valuable data for the fermentation and alcohol production with sweet sorghum stem juice and to make this work have more theoretical knowledge.

References

1. Li Haibin, The substance production and sugar accumulation in sweet sorghum, 1986

The fermentation of sweet sorghum juice for ethanol production with utilization of the technology of immobile cells carrier, as compared with traditional ferment technology, had characteristics of faster working speed, higher productivity and efficiency, shorter action cycle and simpler required equipment. In addition, the continuous and automatic production was achieved easily. The production capacity of the technology could be ten to twenty times more than one of traditional ferment technology. It has been one of the most important improvement and developing direction for ethanol production in the world today. For realizing rapid and continuous fermentation, the key task was to study mass production of gelatinous particles of yeast cells immobilized. It was reported that production of gelatinous particles of yeast cells immobilised in Japan was carried out by use of vibration technology. The solution of yeast cells and carrier were broken into tiny drops. So the yeast cells were embed in calcium keltone. The diameter of spray nozzle for this technology was 1.1 mm, and its maximum productivity was 24 l/h.

The new technology of yeast cells immobilised carrier was studied by Shenyang Agricultural University cooperated with Shenyang Forestry and Soil Research Institute. It was used for extraction of ethanol from juice of sweet sorghum stem. The experiment showed that the thirty percentage of fill factor of gelatinous particles of yeast cells immobilised is needed in the ferment reaction container. So a set of machinery equipment for mass production of the yeast cells immobilized was required. After several experiments, we have developed a pelletizing machine for yeast cells immobilized carrier production. The machine's productivity was 1501/h, 6.25 times more than the one of vibration spray nozzle method at abroad. The study has got a patent in China. The number of the patent licence is 88210233.

4.2.1 Design and Calculation

The equipment was composed of mixer, centrifuge, trough of immobilizing cells and collector of gelatinous particles. The mixer and collector will be introduced separately.

A. Main Structure of the Centrifuge

The centrifuge was made up of electromagnetic governing electric motor, hopper, transmission and centrifuge tray as shown in Fig. 4.2.1.

B. Theoretical Analysis and Calculation

The basic principle of producing gelatinous particles is by use of centrifugal force to break mixed solution of yeast cells with colloid of keltone as carrier into tiny drops, then the drops fall into liquid of calcium in the trough, and then immobilized, the yeast cells are embed by carrier to produce gelatinous particles.

Fig. 4.2.1 Schematic diagram of the centrifuge

When flowing into the centrifuge tray through the hopper and pipe, the mixed solution rotates at uniform motion. The linear velocity of the mixed solution in the centrifuge tray is given as follows:

v = 27p rn/ (60 x 1000) (m/s)

where r is the radius of the centrifuge tray (mm), n is the rotational speed of the centrifuge tray (r/min). According to the second law of Newton, the centrifugal force acting on the mixed solution is given as follows:

F = ma = mv2 / r (N)

where m is the mass of the rotating solution (kg), a is the acceleration of the rotating solution (m/s). The experiments showed that the size of tiny drops which were separated from rotating solution was related to the linear velocity of the centrifuge tray, hole diameter of the centrifuge tray and viscosity of mixed solution. Having selected optimum viscosity of the mixed solution and hole diameter of the centrifuge tray by means of experimental analysis, we concluded that the linear velocity of the centrifuge tray was the main factor influencing mass and size of the tiny drops. If the centrifugal force acting on solution running through the hole of the centrifuge tray was greater than cohesion of the solution, the solution was separated into a tiny drop and thrown along the direction of the linear velocity of the centrifuge tray. Obviously, the faster linear velocity, the smaller the drop, and vice versa. If the linear velocity was so lower that the centrifugal force acting on the solution running out the centrifuge tray smaller than cohesion of the solution, the solution could not be separated into a drop, and flowed out the centrifuge tray in the form of strip. Consequently, according to required size of the gelatinous particles, a range of suitable rotational speed of the centrifuge tray could be determined.

Having been thrown along the direction of the linear velocity of the centrifuge tray, the drops were thrown horizontally in the air. The displacement of the drop was given as follows:

x = vty=gt2/2

where x is the displacement of the at horizontal direction, y is the displacement of the vertical direction, g is the acceleration of the drop, t is the time of the drop moving in the air.

Because of the influence of the centrifugal force and cohesion of the solution, the shape of the drop was not round when it was separated from the centrifuge tray. As the centrifugal force was disappeared and the surface tension of the solution was put into effect, the drop turned gradually into round while it moved in the air. Obviously, the longer the moving time of the drop in the air, the better the roundness shaped. Consequently, the vertical distance from the centrifuge tray to the trough of immobilizing cells and the diameter of the trough could be determined.

After falling into liquid of calcium in the trough, the drops were immobilized. As a result, the gelatinous particles were formed.

C. Measurement and Calculation of the Centrifuge's Power

There were many factors influencing the power of the centrifuge. The calculation of power was more complicated. Hence, technology of electric measurement was used for testing the centrifuge's power. According to the measured moment, the centrifuge's power could be calculated.

a. Main Equipments

The measuring equipment was composed mainly of centrifuge, telemetering strainometer of MRT-220B Model, signal processor of 7T17S Model and so on.

b. Principle and Method of Measurement

Fig.4.2.2 Schematic diagram of the measurement of the centrifuge's power

As Fig. 4.2.2 shown, a thin shaft as elastic element was joined between the electric motor and the transmission. Four strain gauges were stuck on the thin shaft at an angle of 45° with the axis separately. They were wired on the launcher of telemetering strainometer to compose Wheatstone bridge circuit. When the centrifuge was working, the moments acting on the shaft were transferred into electric signals by the telemetering strainometer. The electric signals were launched by the launcher, received by the receiver and recorded on the tape recorder. Sampling and processing of signals through the signal processor, the mean values of the moments were obtained (see Table 4.2.1). The mean value of the power were formulated as follows:

P = Mn/973.6 (kw)

Where M is the mean value of the moment on the shaft (kg-m), n is the rotational speed of the shaft (r/min).

The correlation between the rotational speed and the mean value of the moment (or the power) are given in Table 4.2.1.

Table 4.2.1 shows that the maximum power of the centrifuge is 59.4 w. Hence, a electromagnetic governing electric motor with 0.6 kw power was used to the centrifuge.

Table 4.2.1 The mean value of the moments and the power

Rotational speed (r/min)

No load

On load

Value of the moment (kg-m)

Value of the power (kw)

Value of the moment (kg m)

Value of the power (kw)

120

0.183

0.0226

0.184

0.0227

160

0.184

0.0302

0.192

0.0315

200

0.185

0.0380

0.216

0.0452

240

0.189

0.0466

0.241

0.0594

4.2.2 Experimental Analysis of Producing Gelatinous Particles

A. Determination of the Rotational Speed of the Centrifuge Tray

The experiments showed that the rotational speed of the centrifuge tray was a important parameter. If the rotational speed was too fast or low, the quality of the gelatinous particles would be changed. When the radius of the centrifuge was 900 mm, the optimum rotational speed was from 120 to 240 r/min. Obviously, the greater the required size of the gelatinous particles, the slower the rotational speed that was chosen. Conversely, the smaller the required size, the faster the rotational speed.

B. Quality Analysis of the Gelatinous Particles

There were two main indexes to evaluate the quality of the gelatinous particles: diameter distribution and roundness of gelatinous particles.

a. Diameter Distribution of the Gelatinous Particles

When the hole diameter of the centrifuge tray was 3.5 mm and the rotational speed of the centrifuge tray was from 240 to 120 r/min, the diameter distribution of the gelatinous particles was within the range of 0.5 to 4 mm. If other parameters were altered, the diameter distribution would be changed. The experimental data of the gelatinous particles are given in Table 4.2.2. The experimental conditions were: rotational speed at 160 r/min; the hole diameter of the centrifuge tray of 3.5 mm; preserving for 16 hours; to take sample for 31 times; the weight of each sample 20 g. The samples were classified separately through the classifying screen with different diameter of holes.

Table 4.2.2 The experimental data (1991)

No

Diameter of the particle (mm)

Sample's weight (g)

0.5-1

1-2

2-3

>3

no round

1

0.1

9.5

9.0

1.2

0.2

20

2

0.2

9.4

8.3

1.6

0.5

20

3

0.1

8.8

9.4

1.3

0.4 .

20

4

0.1

8.6

9.9

0.7

0.7

20

5

0.1

8.7

9.3

1.2

0.7

20

6

0.4

8.4

9.5

1.2

0.5

20

7

0.1

8.6

9.7

1.0

0.6

20

8

0.3

8.5

9.3

1.0

0.9

20

9

0.2

8.2

10.0

1.0

0.6

20

10

0.2

8.4

9.4

1.1

0.9

20

11

0.4

9.6

8.7

0.8

0.5

20

12

0.2

9.0

9.0

1.2

0.6

20

13

0.1

9.3

9.0

1.0

0.6

20

14

0.1

9.6

9.1

0.6

0.6

20

15

0.4

8.4

8.6

1.3

1.3

20

16

0.3

11.8

7.2

0.4

0.3

20

17

0.1

12.0

6.8

0.6

0.5

20

18

0.8

12.8

5.5

0.5

0.4

20

19

0.2

12.8

6.1

0.5

0.4

20

20

0.9

12.0

6.3

0.5

0.3

20

21

1.4

13.1

4.9

0.4

0.2

20

22

0.1

12.5

6.5

0.6

0.3

20

23

0.3

12.5

6.5

0.4

0.3

20

24

0.1

13.9

5.4

0.3

0.3

20

25

0.1

12.8

6.2

0.5

0.4

20

26

0.1

12.8

6.2

0.5

0.4

20

27

1.0

14.3

4.3

0.2

0.2

20

28

0.2

12.8

6.1

0.5

0.4

20

29

0.1

13.2

6.0

0.5

0.2

20

30

1.0

13.4

5.1

0.3

0.2

20

31

0.9

12.1

6.1

0.5

0.4

20

Total

10.6

337.8

233.4

23.4

14.8

620

Value

0.3245

10.897

7.5290

0.7548

0.4774

%

1.62

54.48

37.65

3.77

2.39

The statistics of the experiment shows that the gelatinous particles with diameter from 0.5 to 1 mm is 1.62 percent, with diameter from 1 to 2 mm is 54.48 percent, with diameter from 2 to 3 mm is 37.65 percent, with diameter over 3 mm is 3.77 percent.

b. Roundness of the Gelatinous Particles

Under the conditions of previous mention, the roundness of the gelatinous particles could be obtained with same method. The statistics shows that round and elliptic gelatinous particles is 97.61 percent, nonround is 2.39 percent.

4.2.3 Conclusions

The experiments showed that the pelletizing machine for yeast cells immobilized carrier production was successful. Its advantages were high productivity, simple equipment and easy operation.

The diameter range of the gelatinous particles was from 0.5 to 4 mm. This accorded with the demands of the fermentation of sweet sorghum juice.

The pelletizing machine was satisfied with the requirements of the mass production of the gelatinous particles of yeast cells immobilized.

In recent years, energy issue has drawn worldwide attentions. Refining renewable energy from green plants is the major project. Some countries rich in agricultural resources exploit vigorously carbohydrate crops and starch crops to manufacture alcohol and develop alternative fuels. Ethanol fuel is on sale in Brazil, America, etc.. China is an agricultural country, however, as yet grains and resources are not abundant. Therefore, it is not feasible in China to develop alcohol resource with mere grains.

Since 1985, Professor Ma Hongtu of Shenyang Agricultural University, China, has successively bred sweet sorghum varieties of Shennong Tianza No.1, No.2 and No.3. These varieties possess fine properties of being plentiful in both grain and sugar-the seeds may be used as grains, feeds, materials and so on; the juice of stem may be fermented to refine alcohol. The varieties provide a material base for exploiting an alternative fuel in China.

The technology of refining alcohol from juice of sweet sorghum stem is introduced in this paper, including technology of extracting juice from sweet sorghum stem, technology of single concentration fermentation of juice of sweet sorghum stem, technology of fixed yeast fluidized-bed continuous fermentation, technology of refining alcohol with three kinds of materials, and technology of distillation.

4.3.1 Technology of Extracting Juice from Sweet Sorghum Stem

Sweet sorghum stem contains a great quantity of fermentable sugar. The sugar content varies with different years, soil conditions and sweet sorghum varieties. Experimental results (1985) showed that the juice content, for each ton of fresh stem of Tianza No.2; is about 0.78 ton, and the brix degree of sugar content is 15.5°C. To extract juice from sweet sorghum stem, mechanical squeezing technology should be used. Either three-roller squeezer unit juice-extracting system or grinder juice-extracting instrumentation system may be employed.

A. Three-roller Squeezer Unit Juice-extracting System

The juice extraction rate of this technology reaches over 97%. All of the above-mentioned equipments are the product of light industry mechanical factories. When the technology is designed, the production capacity of required equipments must be calculated according to the juice yield per day.

B. Grinder Juice-extracting Instrumentation System

Because it is simple, this system may be employed by factories whose daily yield is less than 7 tons. In contrast to three-roller squeezer unit system, grinder juice-extracting instrumentation system utilizes grinder, screw permeating press and screw drying press, which are the products of light industry mechanical factories, to replace three-roller squeezer unit and after treatment equipments.

This system is simple in structure, economical in investment, easy to operate. There exist some problems to be solved, such as low juice extraction rate (92-94%), strength of screw drying press, wear and tear of drum and leaves.

Fermentation experiments of extracting juice from sweet sorghum stem have been conducted in our university since 1985. The juice-extracting technology with single three-roller squeezer (as shown in Fig.4.3.2) is adopted.

With single squeezer, the juice extraction rate is 50%, and the consumption of electric energy for per ton of stem is 10.8 kilowatt.

The production capacity of equipments must be calculated when the system is designed.

It is a very seasonal work to refine alcohol from juice of sweet sorghum stem. If Shennong Tianza No.2 and No.3 are planted in proper proportions, the reaping period will be from September 15, about 60 days in all. The juice must be refined from harvested stem and then fermented in this period.

If N is the growing area of sweet sorghum in hectares, P the per unit area yield of stem in tons per hectare, T the days of refining alcohol from juice of stem, the production capability of the selected squeezer A, in tons per day, may be calculated by the formula

b. Flow of juice pump

The flow Q1 is

(m³/hr)

where e is the maximum juice extraction rate (about 50-70%), d is the specific gravity of juice (to be regarded as 1 ton per cubic meter).

c. Production capacity of bent sieve

It is calculated by

(m³/hr)

d. Volume of juice storage tank (or pool)

It is calculated by

V1=2Q1

4.3.2 Technology of Fermenting Alcohol from Sweet Sorghum Stem

Juice of sweet sorghum stem contains cane sugar, glucose, fructose, all kinds of amino acids, nitrogen, salt and ash content. They are beneficial to the growth of microorganism.

Either batch (intermittence) fermentation technology (fermentation cycle about 70 hours) or single concentration continuous fermentation technology (fermentation cycle about 24 hours) may be employed for fermenting alcohol from juice of sweet sorghum stem. The advanced technology of fixed-yeast fluidized-bed fermentation, which was developed in recent years by Shenyang Agricultural University and Institute of Applied Ecology, Academia Sinica. Shenyang, makes the alcohol fermentation cycle be shortened to 4-5 hours, thus greatly raising the production rate of alcohol.

Intermittent alcohol fermentation technology that takes juice of sweet sorghum stem as the material is approximately similar to alcohol fermentation technology with other materials. This section mainly introduces single concentration continuous fermentation technology (experimental materials from 1985 to 1986) and fixed-yeast fermentation technology (experimental materials from 1986 to 1989).

Since juice of sweet sorghum stem can flow easily, microorganism continuous fermentation method may be used. Comparing with intermittent fermentation, continuous fermentation is quicker in fermentation process, has higher utilization ratio of the equipment, saves more labour power and material resources, and has lower production consumption. In 1985 and 1986, Shenyang Agricultural University succeeded in refining alcohol from juice of sweet sorghum stem by single concentration continuous fermentation technology. The technological process is shown in Fig.4.3.3.

The operation procedure is as follows. The gradually cultured distiller's yeast is poured into the No.1 tank (8). Then, in the proportion of 1 to 10, juice of sweet sorghum that has been heated and sterilized (the pH value is 4.5-5) is introduced into the tank until it is full. When the temperature is 30 °C, lead aseptic gas into the tank intermittently to culture bacterium for 18-24 hours. After the yeast has reproduced, open the valves of the cooling tank. Let juice of sweet sorghum flow into the tank through the upper inlet of the No.1 tank (8) at a speed of v1'. Then, nutriment is provided for the saccharomycete to advance it to reproduce in a large quantity. Juice should be continuously added into the No.2 tank (8) at a speed of v2' while being filled into the No.1 tank (8). To accelerate the reproduction of yeast, aseptic gas should be pumped intermittently into the No.1 and No.2 tanks (8). The flow indexes are 2-2.5m³/hr for per ton of juice and 10 minutes of air flow once every one hour. Juice should also be added into the No.3 tank (9) at a speed of v3' while being filled into the No.1 tank (8), passes through other tanks in serial mode, and flows out from the No.10 tank (9). This procedure takes about 24 hours and above 80% of sugar juice could be fermented to become alcohol and CO2

Table 4.3.1 Technological Conditions of Tank

Names of tank

Code number

Temperature (°C)

pH value

Notes

juice storage tank

1

normal temperature

7

heating and sterilizing tank

3

60

4-4.5

adjust pH value by adding acid, keep 30 minutes.

Cooling tank

6

28-30

4-4.5

three tanks are utilized alternatively

yeast tank

8 (the No.1 and No.2)

34

4-4.5

introduce aseptic gas for culture. Set up cooling coil.

Fermentation tank

9 (the No.3-7)

34

4-4.5

anaerobic fermentation

fermentation tank

9 (the No. 8 and No.9)

30-32

4-4.5

anaerobic fermentation, in the end of the period

Chuan No. 102 saccharomycete was used in this used in this technology.

During normal operation, the inlet valves of the No.1 tank (8), No.2 tank (8) and the No.3 tank (9) should be opened at the same time. Juice flow needs to be filled into the three tanks. The amounts of juice flow, presented as v1', v2' and v3' respectively, are given by

V1'=0.6.· B/24

(m³/hr)

V2'=0.14· B/24

(m³/hr)

V3'=0.26· B/24

(m³/hr)

[calculation for flow of fermentation beer]

After beer has fermented in the No. 10 tank (9), it flows out from the upper outlet of the tank. Suppose the flow is Ve,

(m³/hr)

Where bx is the sugar content of juice of sweet sorghum, f is the loss rate of juice during fermentation and the value of f is assumed to be about 10%, C is the fermentation rate of juice and Ç is about 85%, is the theoretical conversion rate of CO2 and equals 51%.

[calculation for the production capacity of required distillation column]

If two columns or three columns are employed, alcohol of above 95% could be distilled from fermentation beer. The production capacity of distillation column (tower) must be designed to match the amount of fermentation beer. The production capacity of the column is

C=B (1-f) bx· Ç·d·b· d

(ton/day)

Where b is the distillation rate of alcohol (b =94%), Ç is the theoretical conversion rate of alcohol (Ç=54%).

The distillation columns employed in this technology are identical to those columns used in alcohol production with sugar and honey.

The new fermentation technology through fixed yeast fluidized-bed is an advanced biological technique in the world of today. Comparing with batch fermentation and /or single concentration continuous fermentation, the new fermentation technology possesses the advantages of quick speed, shout fermentation cycle, high yield, few instruments, and it is easy to realize automation. The production capacity of the new technology is 10 to 20 times as high as that of batch fermentation. In order to develop the technology of refining alcohol from juice of sweet sorghum stem, to reduce equipment investment and to improve economical benefits, our university and Institute of Applied Ecology, Academia Sinica, have jointly engaged in the research work on this new technology. A 286ml CH-1 type glass reactor, a 2800ml CH-2 type glass reactor and a SOL CH-3 type stainless steel reactor were designed successively. To observe inner reaction and grasp reaction mechanism, a SOL polymethyl methacrylate reactor was designed. In September, 1989, a 450L reactor and the complete set of technological equipment were designed again. Experimental result showed that the design requirements are satisfied.

Tests show that, since the contact area of fixed-yeast carrier and juice is large, the reaction rate is increased and the fermentation cycle is shorten to be 4 to 5 hours. Because fixed-yeast reproduces unceasingly in the carrier and is not easy to become ageing, the life span of yeast is prolonged, the discharge of organism is reduced, and the environmental pollution is alleviated. Moreover, because the biological reactor is a kink of dumbbell-shaped three-unit vertical equipment, the volume is small, the ground area it occupies is little, and the capital construction investment is greatly decreased. In order to cooperate with the project of "The Energy Integrated Demonstration Base for China's Cold Northeastern Region", technology and equipments of fixed-yeast, which achieves a daily yield of 400 kg alcohol, was designed by the author.

a. Technological process

The technological process of refining alcohol through fixed-yeast fluidized-bed biological reactor is shown in Fig. 4.3.5.

Before normal operation of this system, fixed-yeast cells must reproduce. The prepared fixed-yeast particles are filled into the first unit of the reactor. Then, diluted juice of sweet sorghum is introduced into the reactor until it is full. At the same time, aseptic gas should be led in continuously to make fixed-yeast cells to reproduce. This process lasts about 50 hours. When cells reproduce from 106 to 108 per millilitre solution, and the sprouting rate rises from 5-10% to 15-30%, fermentation stage begins.

When normal operation begins, CO2 circulation system and juice flowing and filling system should be started simultaneously. CO2 in the gas bag is pumped into the constant pressure gas storage tank by the No.1 gas compressor. Then, CO2 is led into the gas chamber at the lower end of the biological reactor. Passing through the gas dispersing plank, it eventually enters the reactor and forms the reaction force. Thus, the force makes fixed-yeast particles react inside the third unit of the reactor. At the same time, juice of sweet sorghum inside the high position tank, under the action of pressure, injects into the reactor from two tangentially-mounted spouts in the first unit of the reactor and circulates around the axis. Acted simultaneously by the upward force formed by CO2, juice moves in a upward spiral way. The solid-liquid-gas three-phase flowing layer (shown in Fig.4.3.6) that was formed in the reactor makes the CO2 gas adhered to the surface of fixed-yeast particles be released

Fig.4.3.6 Moving law of fluidized bed in the reactor

As CO2 gas constantly contacts with fermentation liquid, vigorous reaction state is maintained and the reaction rate is greatly increased. Since juice entered from the tangential spouts in the first until of the reactor, it takes about 5 hours for juice to pass through all of the three units and carry out the reaction. Above 90% of sugar is converted into alcohol and CO2. The eventually formed fermentation beer enters beer storage chamber, and them flows into solid-liquid separator through the outlet. After broken remains of yeast particles have been removed, fermentation beer is introduced to beer storage trough to be distilled.

CO2 gas coming out from the third unit is pumped into CO2, storage bag through beer storage chamber, foam collector, gas-liquid separator and cooling and purifying tank by the compressor. It is prepared to be used next time.

b. Technical data of fermentation technology

During continuous fermentation, constant reaction force must be maintained, juice of sweet sorghum needs to be added evenly, and the temperature and pH value inside the reactor should be retained unchangeable. The above-mentioned indexes are all monitored by meters. The parameters for maintaining continuous fermentation are obtained by a number of tests and listed in Table 4.3.2.

Table 4.3.2 Parameters of fixed-yeast fermentation technology

juice flow (m³ /hr)

temperature of the first and second units (°C)

temperature of the third unit (°C)

pH value of three units of the reactor

temperature of beer store chamber (°C)

pressure of beer chamber (mm Hg)

the ratio of inlet gas flow to exhaust gas flow

operation parameter

Q=B (1-f) /24d stable

32-34

30-32

4.5-5

20-30

0 - 50

1: 6-10

monitoring meters

flowmeter

thermometer

thermometer

sample

thermometer

vacuum meter

gas flowmeter

c. Experimental results of fermenting juice with fixed-yeast

The continuous and partially continuous fermentation experiments were conducted with juice of sweet sorghum.

After juice of sweet sorghum of 10% sugar content has been fermented for 4 hours, the alcohol yield will be 6.2% (v/v) and the conversion rate will be 48% that is over 90% of the theoretical conversion rate. Fig.4.3.7 shows the variation of parameters during fermentation process of juice of sweet sorghum.

Fig.4.3.8 Variation of parameters during fermentation process of juice of cane sugar.

Where La0.3-0.5.m and PL 40-100 mm (PL is the readings of Vacuum meter).

DR=D0

(m)

DL=D

(m)

K1=LR=La+ Lb

(m)

K2 =I5 DL

(m)

where I5=0.28-0.5

K3 =DR/4+ 0.0025

(m)

K4=0.5m

[design and calculation for foam collector]

The structure of foam collector is similar to that of alcohol distillation column.

The usually employed collector has 12-15 planks. The distances between planks are 120-150mm. Because the technology of fixed-yeast fluidized-bed fermentation is different from other fermentation technologies, the diameter of column can not be calculated with the formulas adapted to conventional fermentation technologies. Experiential formula for calculating column diameter was drawn from numerous facts by the author. It is

Dp=0.1904· (B· (1-f)· bx· Ç· s)1/2

(m)

where B=eA

The column diameter of foam collector for less than 2 tons of alcohol yield per day may select Dp- 0.34m. Figure 16 shows the structure of juice filling column foam collector designed by the author.

[design and calculation for gas-liquid separator]

The structure of gas-liquid separator is shown in Fig.4.3.15. The role of gas-liquid separator is to make the thin alcohol to sink further inside it for recovering. According to experimental data, several experimental formulas are given as follows.

Dy= (13.6· 0.06452m· B· (1-f)· b· Ç·b· T· Dk2)l/2

(m)

(m)

where t=30-60s; m may be chosen from 5, 4, 3, and 1; Tw is the temperature inside foam collector (usually Tw3300K); Pb is the negative pressure of foam collector (Pb0.947 at atmospheric pressure).

Only by maintaining the production all the year round can a system of refining alcohol increase the utilization ratio of equipment and the economical benefits. Therefore, in the project of EIDBCCNR, integrated technology of refining alcohol from three kinds of materials - sugar, starch and juice of sweet sorghum should be employed, Fig.4.3.19 shows the technological process of refining alcohol with three kinds of materials designed by the author, in which the system of refining alcohol with juice of sweet sorghum and waste sugar utilizes fermentation technology of fixed yeast biological reactor while the system of refining alcohol with starch employs fermentation technology of neither steaming nor boiling.

The No.5 tank was designed in terms of fermentation technology of raw starch. It possesses stirrer, cooling coil, inlets for steam and aseptic gas, etc... When fermentation technology of fixed-yeast biological reactor is implemented, the three tanks are used to store cool juice. When fermentation technology of neither steaming nor Boiling is carried out, the tanks are provided for stirring, saccharifying and fermenting. Here, heating and sterilizing tank may be used to activate highly active dry yeast.

b. Fermentation technology of fixed-yeast biological reactor

This system is only suitable to refine alcohol with juice of sweet sorghum and waste sugar. The fermentation technology is introduced in section B.

To ferment starch using highly active dry yeast without steaming and boiling is also an advanced technology that has been developed lately in alcohol industry. It has the advantages of saving resources, decreasing equipment investment, reducing costs and is fit to be employed together with technology of fixed-yeast.

Activation technology of highly active dry yeast

Table 4.3.5 Indexes of yeast Juice when Activated

cells (millions per millilitre)

gemma

useless bacteria

death

37.1

14.4%

none

none

Pump fresh distiller's grains into the heating and sterilizing tank, add water to lower the temperature to be 40° C and the pH value 4.5-5. Then, put in 6% of the active dry yeast and keep the temperature at 40° C (temperature maintained by heating the coil inside the heating and sterilizing tank). After 2 hour, juice of highly active yeast will be obtained. The active indexes are listed in Table 4.3.5.

Fermentation technology of neither steaming nor boiling

When juice of distiller's grains (above 70%) that is just exhausted is pumped by slurry pump into the fermentation tank, the thin starch (filtered by 20-screen sieve or 80% filtered by 40-screen sieve) is added to the tank in proportion of 3 to 1. Then, the stirrer is started. After the evenly stirred starch has been braised for 40 minutes, the starch particles are fully expanded. Open the valve of cooling pipe and lower the temperature at 55 ° C. Then, in proportion of 5%, leaven (Heiqu No.2) is put in and the stirred is started again. After if has been mixed evenly, lead in cooling water to lower the temperature continuously. When the temperature drops to 29-30°C, cool water (the ratio of material to water is 1 to 1) is added. When the temperature drops to 25-26 °C, open the outlet valve of heating and sterilizing tank to let the activated yeast (in proportion of 10%) flow into the fermentation tank. Then, seal the tank. After 68-72 hours of fermentation, beer is formed and put in the beer storage for distillation.

4.3.3 Distillation System

After juice of sweet sorghum has been fermented to become beer, the distillation system is needed to distil and refine alcohol of above 95% (v/v). Distillation column can be chosen according to conventional technology for distilling beer. Fig.4.3.20 shows the technological process of alcohol distillation.

The distillation technology in "The Energy Integrated Demonstration Base for China's Cold Northeastern Region" is the part of distillation system shown in Fig.4.3.20. Two columns for distillation were adopted in this technology. The rough distillation column is about 7460 mm high, comprised of 25 planks. The rectifying column is divided into two sections to lower the height of the distillation workshop. Each of the two sections is 10000 mm high and has 40 planks. Round-shaped cover structure of planks is suitable for distilling the three kinds of fermentation materials. Alcohol travels from rough distillation column to rectifying column (1) in steam phase. The recycling liquid from rectifying column (2) is pumped back into rectifying column (1).